The evaluation and analytical comparison of competing therapies for various types of cancer is not only a fundamental problem, but one which is rapidly becoming more acute as research in oncology progresses. Without the appropriate statistical tools to evaluate and monitor the information now being generated in this area of national concern, important developments may be delayed or overlooked. This grant request presents a comprehensive approach to the problem which not only utilizes existing theory and data but also will provide the necessary sophisticated tools for the comparison of therapies. The basic objectives of this grant request are the investigations and statistical modeling of survival data of patients having various types of cancer and who are subjected to different therapies. The usual life table method of estimating survivorship assumes a constant mortality rate in each class interval. This and the present assumption of constant mortality rate for all risk factors, whether disease oriented, extraneous, or induced, though simple, is neither accurate nor realistic. We propose the development and assessment of more appropriate statistical techniques. Using theory developed for reliability studies where concomitant competing risks are present, this approach will overcome to a large extent the major shortcomings of available methods. Application to clinical data for various treatments and types of cancer will be carried out in conjunction with the proposed technical developments.